The characteristics of existing sternal skin conductance monitors that hinder use under ambulatory conditions and for long tern data collection are that they are too bulky to be cosmetically acceptable, have distracting wires, and weigh too much. We propose to characterize hot flashes by measuring the frequency, timing, and the amplitude of hot flashes using sternal skin conductance. Our chosen approach is to develop a miniature ambulatory recorder that is precise, functional, and aesthetically appropriate. We have assembled a team with expertise in required fields to implement the application goals. Team members include a clinical collaborator to supervise testing on a sample of menopausal women, a biomedical engineer experienced in electrode testing, a small business biomedical engineer experienced in the design and development of miniature medical instruments, and a biomedical engineer experienced in both miniaturization and conductive adhesive polymer testing. Our team will develop and test an unobtrusive (no wires) miniature instrument to objectively measure and record hot flashes. Our specific aims are: 1-Meet with a menopausal women's focus group to gain information on preferred approaches. 2-Develop electrode and electrolyte compositions that stabilize skin conductivity. 3-Design an electronic and electrode package and test the prototype in the laboratory. 4-Design and implement hot flash pattern recognition software. 5-Manufacture 6 instruments and test on a small supervised group of women with documented hot flash occurrences. 6-Redesign as necessary, manufacture 30 instruments and test on a large unsupervised group of menopausal women representing a spectrum of hot flash occurrence (20 women with at least 5 daily and nightly hot flashes, 5 women with less severe hot flashes(< 5 daily) and 5 women who do not experience hot flashes. 7-lnvestigate the data quality under ambulatory conditions of typical daily living 8-Compare the objective data (proposed monitor) with subjective data (subject recorded hot flashes).